(P0303) Cylinder 3 Misfire Detected; rough idling
02-09-17, 08:22 PM
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(P0303) Cylinder 3 Misfire Detected; rough idling
Hello!
My friend's car is having a bit of a hiccup, and he's a little tight around the budget, so I am asking for some wisdom here!
1999 Lexus ES300, Less than 95k miles, smog test passed in Jan of 2017, Knock sensors (bank I & II) and Intake manifold Gasket replaced in December.
Codes running before the last repair were (P0325); Knock sensor 1 circut malfunction & (P0338); which doesn't show up in the manual.
About two weeks ago, shortly after a gas-fill up (usual station, usual octane grade) the car started idling roughly after 3rd or the 4th complete stop.
- Check Engine Light came on along with Trac Off
Route was all local, not exceeding speeds more than 35mph.
P & N gears would lighten the shake, but when in any other gear, the car would shake pretty noticeably.
Got a bit thrown off, pulled over to the nearest curb and shut the engine off.
- Popped the hood and did smell something burning. No smoke present. Smell disappeared quickly.
- Tried turning the engine on, and nothing. Bleep. No dash lights, no sounds, no nothing.
- Got scared, waited for another minute. Tried again, voila. Engine runs, still with the shake, and with the CEL and Trac Off light.
- Turned the engine off again. Waited about 5 minutes. Called some friends. Turned it on again, and same deal. Didn't turn over the first time, worked the second time.
- Putting it into gear from P right after ignition would actually stall the engine; had to wait a couple seconds, then put it into gear to not stall the engine.
Didn't drive it for good reasons, and set up an appointment at a local lexus specialist auto repair shop.
On the way to the shop, the CEL started blinking, still with the Trac Off light. Did sense a bit of power loss in acceleration.
Mechanic said, it could be a number of reasons, and could run up to $1000 +/- even for a spark plug & ignition coil replacement. He did mention that Trac Off light usually means something else.
Didn't have $1000 to spare, so we ran out of there.
Called a couple others, but they would all say the same and insist they take a look at it for $100-130. Only then they could tell what's up.
Bought an OBD II checker online, because it was cheaper than the full diagnostics done by a real mechanic, and the code is running (P0303).
Cylinder 3 Misfire Detected
I did try pulling the battery to reset, and the shaking dampened a little bit and stayed that way.
Unfortunately, I did this before I got the OBD II reader, so I have no idea if there were other codes existent before the reset.
Did check a couple times while idling; and just checked another time after driving around the block.
Manual is saying it could be any of these:
-Ignition system
-Injector
-Fuel line pressure
-EGR
-Compression pressure
-Valve clearance not to specification
-Valve timing
-Mass air flow meter
-Engine coolant temp. sensor
My friend heard from another friend that this is a classic spark plug & coil issue, and doesn't want to spend $130 just to find out that he doesn't have the money to fix the issue.
He'd rather spend $200ish and chance it that it indeed is just a spark plug and coil issue.
What's the wisest thing to do here?
Call up a mechanic and skip the diagnostics and tell him that we just want #3 spark plug and coil replaced in knowing that that might not be the root cause, and see if he would agree to the job?
Does this sound stupid only to me?
Please help. Thank you!
My friend's car is having a bit of a hiccup, and he's a little tight around the budget, so I am asking for some wisdom here!
1999 Lexus ES300, Less than 95k miles, smog test passed in Jan of 2017, Knock sensors (bank I & II) and Intake manifold Gasket replaced in December.
Codes running before the last repair were (P0325); Knock sensor 1 circut malfunction & (P0338); which doesn't show up in the manual.
About two weeks ago, shortly after a gas-fill up (usual station, usual octane grade) the car started idling roughly after 3rd or the 4th complete stop.
- Check Engine Light came on along with Trac Off
Route was all local, not exceeding speeds more than 35mph.
P & N gears would lighten the shake, but when in any other gear, the car would shake pretty noticeably.
Got a bit thrown off, pulled over to the nearest curb and shut the engine off.
- Popped the hood and did smell something burning. No smoke present. Smell disappeared quickly.
- Tried turning the engine on, and nothing. Bleep. No dash lights, no sounds, no nothing.
- Got scared, waited for another minute. Tried again, voila. Engine runs, still with the shake, and with the CEL and Trac Off light.
- Turned the engine off again. Waited about 5 minutes. Called some friends. Turned it on again, and same deal. Didn't turn over the first time, worked the second time.
- Putting it into gear from P right after ignition would actually stall the engine; had to wait a couple seconds, then put it into gear to not stall the engine.
Didn't drive it for good reasons, and set up an appointment at a local lexus specialist auto repair shop.
On the way to the shop, the CEL started blinking, still with the Trac Off light. Did sense a bit of power loss in acceleration.
Mechanic said, it could be a number of reasons, and could run up to $1000 +/- even for a spark plug & ignition coil replacement. He did mention that Trac Off light usually means something else.
Didn't have $1000 to spare, so we ran out of there.
Called a couple others, but they would all say the same and insist they take a look at it for $100-130. Only then they could tell what's up.
Bought an OBD II checker online, because it was cheaper than the full diagnostics done by a real mechanic, and the code is running (P0303).
Cylinder 3 Misfire Detected
I did try pulling the battery to reset, and the shaking dampened a little bit and stayed that way.
Unfortunately, I did this before I got the OBD II reader, so I have no idea if there were other codes existent before the reset.
Did check a couple times while idling; and just checked another time after driving around the block.
Manual is saying it could be any of these:
-Ignition system
-Injector
-Fuel line pressure
-EGR
-Compression pressure
-Valve clearance not to specification
-Valve timing
-Mass air flow meter
-Engine coolant temp. sensor
My friend heard from another friend that this is a classic spark plug & coil issue, and doesn't want to spend $130 just to find out that he doesn't have the money to fix the issue.
He'd rather spend $200ish and chance it that it indeed is just a spark plug and coil issue.
What's the wisest thing to do here?
Call up a mechanic and skip the diagnostics and tell him that we just want #3 spark plug and coil replaced in knowing that that might not be the root cause, and see if he would agree to the job?
Does this sound stupid only to me?
Please help. Thank you!
02-09-17, 11:12 PM
#2
Lead Lap
P0338 - Crankshaft Position Sensor 'A' Circuit High Input
Read more: https://www.autocodes.com/p0338.html
do you guys have tools, or spanners, and stuff. because it's going to be way cheaper to turn some spanners on this yourselves.
if it was my car, I would get some used parts and swap those in.
Read more: https://www.autocodes.com/p0338.html
do you guys have tools, or spanners, and stuff. because it's going to be way cheaper to turn some spanners on this yourselves.
if it was my car, I would get some used parts and swap those in.
- I would remove all the spark plugs and lay them out in order and read the colours of them.
- I would probably remove the spark plug on that cylinder, and replace it with a new one, (actually i'd do them all).
- I would check the coil leads for a good connection, and likely replace the spark plug lead to that cylinder.
- this 'mis fire' is a failure to fire, hence the shaking.
02-12-17, 08:13 AM
#3
Bad knock sensors can cause the symptoms you described. But I'd expect the error code to show up again. Another common problem causing misfires is the OCV but usually you get misfires on all the cylinders on one bank.
The trac off light is probably a sympathetic code so the traction control is probably fine. The computer turns it off because of the other problems.
If the only error code being reported is a single cylinder misfire I'd look at the the spark plugs or the ignition coil (about $60 from Rockauto for a Denso brand coil) for that particular cylinder. You can switch coils to see if the misfire follows the coil. Too bad you didn't change the spark plugs when the knock sensors were replaced.
If it were mine I'd replace all the spark plugs and move the #3 coil to a bank two cylinder because I'm too lazy to do all the work getting to the #3 coil more than once. Worst case, I'd have new iridium spark plugs (which at 95,000 miles are probably due to be replaced anyway) and moved the potentially bad coil to a more accessible location where if it is bad is easily replaced.
The trac off light is probably a sympathetic code so the traction control is probably fine. The computer turns it off because of the other problems.
If the only error code being reported is a single cylinder misfire I'd look at the the spark plugs or the ignition coil (about $60 from Rockauto for a Denso brand coil) for that particular cylinder. You can switch coils to see if the misfire follows the coil. Too bad you didn't change the spark plugs when the knock sensors were replaced.
If it were mine I'd replace all the spark plugs and move the #3 coil to a bank two cylinder because I'm too lazy to do all the work getting to the #3 coil more than once. Worst case, I'd have new iridium spark plugs (which at 95,000 miles are probably due to be replaced anyway) and moved the potentially bad coil to a more accessible location where if it is bad is easily replaced.
Last edited by tomf; 02-12-17 at 08:36 AM.
08-20-20, 09:14 PM
#5
Driver School Candidate
More updates after a cool evening here finally. First the bad.
.. Got a power steering leak somewhere haha. The good being that after messing with trying to clean connectors and other stuff I finally got around to just pulling the ignition coil off #s 4 and 6 and swapped them. And the misfire followed it to #4. So I just ordered one online seeing as every parts store around me was trying to charge nearly $100 for a single coil. Tomorrow morning I'm going to look around for the power steering leak before it gets hot out and hopefully find it without too much trouble. Topped it off tonight and saw a big puddle pretty quickly. I plan to just throw some in and hopefully be able to see where it's from
.. Got a power steering leak somewhere haha. The good being that after messing with trying to clean connectors and other stuff I finally got around to just pulling the ignition coil off #s 4 and 6 and swapped them. And the misfire followed it to #4. So I just ordered one online seeing as every parts store around me was trying to charge nearly $100 for a single coil. Tomorrow morning I'm going to look around for the power steering leak before it gets hot out and hopefully find it without too much trouble. Topped it off tonight and saw a big puddle pretty quickly. I plan to just throw some in and hopefully be able to see where it's from
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